Independent mirror swing-up means in a single lens reflex camera with memory exposure device

Abstract

A manually operable mirror swing-up lever is associated with an exposure information memorizing device. The exposure information memorizing device has a locking lever which locks a sliding contact movable on a variable resistor at a position representing the exposure information. The variable resistor is connected in parallel with a memory capacitor in an electric circuit for controlling an electric shutter. The terminal voltage of the variable resistor is controlled to be equivalent to the terminal voltage of the memory capacitor. When the mirror is swung up by the manually operable mirror swing-up lever, the sliding contact is locked in position to make the variable resistor work as an equivalent for the capacitor, and the resistor is substituted for the memory capacitor.

What is claimed is: 
     
       1. In a single lens reflex camera having a focal plane shutter, a mirror automatically swingable from a reflecting position to a folded position by means of an automatic mirror swing up means, in response to the release of the shutter of the camera, a memory type electric shutter control means having a memorizing capacitor and circuit means controlling the operation of the focal plane shutter in the camera, a taking lens, the quantity of light passing through the taking lens being measured by a photoelectric element located in a view finder optical system receiving the light reflected from the mirror, the output of this photoelectric element being connected to said memorizing capacitor in the memory type electric shutter control means, and an electric power supply for the memory type electric shutter control means the improvement comprising: a variable resistor connected across said electrical power supply, means for swinging the mirror to the folded position independently of the release of the shutter, electrical responsive means having a needle movable in response to an electrical potential applied thereto and being connected in parallel with the memorizing capacitor, said needle forming a contact for said variable resistor, the position of said needle being determined by said potential which exists across terminals of the memorizing capacitor, a switch-over means for selectively coupling the memorizing capacitor or the variable resistor to circuit means in the electric shutter control means, locking means operatively connected between said means for independently swinging the mirror and said slidable contact, said locking means fixing the position of said slidable contact on said variable resistor and operating said switch-over means to connect said variable resistor in, and to disconnect said memorizing capacitor from, said circuit means when said means for independently swinging said mirror to its folded position is operated. 
     
     
       2. In a single lens reflex camera as defined in claim 1 wherein said electrical responsive means is a galvanometer. 
     
     
       3. In a single lens reflex camera as defined in claim 2 having a view finder optical system, wherein said slidable contact is a needle of said galvanometer made of conductive material. 
     
     
       4. In a single lens reflex camera as defined in claim 3 wherein the end of said needle of the galvanometer is projected into said view finder optical system so that said end may be viewed through the view finder system. 
     
     
       5. In a single lens reflex camera as defined in claim 4 wherein a shutter speed scale is provided along the path of the movement of the end of the needle. 
     
     
       6. In a single lens reflex camera as defined in claim 1 wherein said locking means is a rotatable locking lever having a portion to hold said slidable contact on said variable resistor and a portion to operate said switch-over means, by the rotation of said lever in one direction the switch-over means is turned from said memorizing capacitor to said variable resistor and the slidable contact is held on the variable resistor. 
     
     
       7. In a single lens reflex camera as defined in claim 6 wherein said means for independently swinging the mirror includes a manually rotatable mirror swing-up lever interconnected with said locking lever, said locking lever being rotated in said one direction when the manually rotatable mirror swing-up lever rotated to swing the mirror to the folded position. 
     
     
       8. In a single lens reflex camera as defined in claim 7 wherein an interconnection lever is connected with both said manually rotatable mirror swing-up lever and said locking lever for transmitting the movement of the former to the latter, said interconnection lever being biased to move the mirror swing-up lever in the direction to return the mirror from the folded position to the reflecting position. 
     
     
       9. In a single lens reflex camera as defined in claim 7 wherein there is provided a power supply switch in series with said electrical power supply, said manually rotatable mirror swing-up lever being provided with a switch operating means which closes said power supply switch when said mirror swing-up lever is moved in the direction to swing the mirror to the folded position. 
     
     
       10. In a single lens reflex camera as defined in claim 9 wherein there is provided a manually operable power supply switch in series with said electrical power supply, said power supply switch being connected in parallel with said manually operable power supply switch. 
     
     
       11. In a single lens reflex camera as defined in claim 1 wherein said switch-over means is a change-over switch comprising a first stationary contact connected with said memorizing capacitor, a second stationary contact connected with said slidable contact and a third contact connected with the shutter control circuit means, said third contact being selectively movable into contact with said first and second contacts, and said locking means is a locking lever operatively connected with said means for independently swinging said mirror to its folded position and movable between a first position and a second position, in the first position of the locking lever the slidable contact being free to slide on the variable resistor and the mirror being in its normal reflecting position, and in said second position the locking lever holding the slidable contact on said variable resistor and the mirror being in its folded position, and said locking lever is provided with a switch operating means which moves said third contact into contact with said first contact when the locking lever is moved into said first position and moves said third contact into contact with said second contact when the locking lever is moved into said second position. 
     
     
       12. In a single lens reflex camera as defined in claim 11 wherein said switch operating means is a cam attached on said locking lever, and said third contact is biased to follow the cam. 
     
     
       13. In a single lens reflex camera as defined in claim 11 wherein said means for independently swinging said mirror to its folded position is a mirror swing-up lever pivotally mounted on a fixed shaft and operatively connected with a manually operable knob so as to be moved thereby between a first position to set the mirror in the normal reflecting position and a second position to keep the mirror in the folded position. 
     
     
       14. In a single lens reflex camera as defined in claim 13 wherein there is provided a power supply switch in series with said electrical power supply, and said mirror swing-up lever is provided with a switch operating means to close said power supply switch when the lever is moved from said first position to said second position.